Electrical transformer core or magnetic circuit



se t.'13,192 l p 7 c. M. WELCH 1642470 ELECTRICAL TRANSORMER CORE OR MAGNETIC CIRCUIT Filed oct. 24. 1921 Patented Sept. 13, 1927.

CHARLES M. WELCH, OF OGDEN, ARKANSAS.

PATENT OFFICE.

ELECTRICAL TRANSFORMER CQRE OR MAGNETIC CIRCUIT".

Application tiled October 24, 1921. Serial No. 510,168.

The object of my invention is to secure a form of transformer core which will render the magnetic circuit leasy to build and the coils easy to wind, and utilize the maximum available core area with a circular cylindri- Cal coil and a magnetic circuit built of laminated sheet material.

The invention will hereinafter bemore particularly described as embodied in a two coil, single magnetic closed circuit 'transformer. y This general type is commonly employed in wireless radio, instrument transformers, high voltage sets, bell ringers and toy transformers and the like. Apparatus of this general type have not heretofore been built extensively for commercial light and power distribution. I believe my improvement is further novel and useful in the design of small capacity high or. low voltage transformers for general work.

The specifications, drawings and claims set forth herein what I believe to be the points of novelty in my present invention, and whereas other arraiigements and modifications may be made, I intend to'cover all such arrangements and modifications which do not depart from the spirit and scope of my invention. l

Those skilled in the art will readily under- 3) stand that my invention may be embodied as a means of constructingv a set of series of magnetic circuits to operate as integral part units extending over a wide range of appliations, and I do not restrict my improvement in whole, or, in part, to any specific usage which does not depart from the spirit and scope of my invention.

Referring to the drawings, similar letters refer to similar parts throughout the several views, in which:

Fig. 1, is a cross sectional elevation taken on line 1-1 in Fig. 2, and shows the arrangement of the core part members through the coil portions: Fig. 2, represents a side elevation of the assembled core with coils in which the upper portion is shown broken away along the broken lines illustrating the part members: Fig. 3, is a perspective view of my bent end yoke laminas: ltig. 4, is a side elevation of the assembled core without the coils and illustrates inl part the method of interleaving the laminas and also further Aidentifies the part members: Fig. 5, is a vertical cross sectional elevation through a portion of the depending core leg shown outside the coils in Fig. 2, and further illustrates the method of interleaving the laminas: Fig. 6, is a cross sectional elevation taken on line` 6 6 in vF ig. 9., illustrating in detail the laminas and completes the illustration of the method of` forming and joining their parts' together.

I provide my coil bearing core leg C wit-h laminated members each departing from the plane of theother in which laminas of the same size may be employed to produce the polygonal core cross section through the coils'P and S shown. The section member Cl is composed of parallel laminas offset relative to each 'adjacent laminaeto produce surfaces substantiallyv V-sha'ped` in cross section. The section member C2 is composed of other parallel laminas oset relative to each. adjacent laminas to produce surfaces substantially rhomb-shaped in cross section. The rhomb-shaped` member fits along side in the V-sh'aped member, whereby the core leg C assumes Asubstantially hexagonal section. p v

I place a depending core leg C3 outside the coils. This leg Cs is composed of arallel laminae' offset relative to eachadjacent laminas to produce surfaces substantially V- shaped in cross section. I place this leg C3 parallel with the section member C1 thereby forming two depending members with ra space between them Vfor vthe coil thickness. The passage for the coil thickness is not straight through but assumes a shape corresponding to the sides of the adjacent members, whereby the coil tits snug iny the openmg.

The laminae composing the members C1, C2, and C3, may be of the same size and same length. In order to provide for joining these members together across their opposite ends with yoke laminae, hereinafter described, I stack the core leg laminas through the coils so that each alternate laminae or multiples thereof is extended from the coil end face and on both ends forming slots of equal depth into which the Vinterleaving end yoke laminas may lie. And, of course, I prepare the depending core leg C3. laminae in similar fashion corresponding to the other core leg laminas. The C1 section member lamin are represented by 2: the C2 section member laminas by 1: and the C3 depending leg member laminas by 3.

The top and bottom end yokes Y are composed of yoke lamina@ of the same Width and two lengths. The short yoke laminae Y2 and Y3 are of the same size. The long yoke laininae Y1 is longer by approximately the Width of one of the core laminae than the other' yoke laminae. This long yoke laminae Y1 has a bent end as illustrated in Fig. 3, which is secured by bending the laminze fiat- Wise at an angle corresponding to the plane of the laminae in section member C2. In the assembly of the yoke laminae I may use single laminae or multiples thereof corresponding to the number of laininae placed in a cluster in the core members as stated above, it being conventional practice to use relatively thinl laminae and stack them in clusters of tvvov or three in conventional transformers, which isV an obvious expedient and I point itout to show the conventional application. The bent end yoke laminze Y1 is interleaved with the leg` laminae in the section member parts C1 and C2 thereby joining these parts together, whereby the plane of the laminae in C2 relative to the plane of the laminae in C1 determines the degree of angle of the bent angle laminze. Yoke laminae Y2 are interleaved With the core laminzeJ remaining in C1 and the core is joined up' complete by interleaving the yoke laminae Y3 with core laminae C3 and withV the projecting yoke laminze Y1 and Y2 thereby completing the magnetic circuit through common end yokes assuming substantially rectangular section through their middle portions. The core may be clamped in any conventional Way by compression means.

Because. the trough of my V-shaped section member C1 lits With tWo sides of my rhomb-shaped section member C2 a complete core section C is produced composed of laminations of the same size assembled Within a circular coil, whereby an effective core area approximately equal to a circumscribed hexagon is secured.

As will be readily understood from the drawings, die core C is substantially hexva-gon section, the depending leg C3 a V-shape section-, and the yokes Y adjacent the coils have'substantially rectangular section, which renders a novel and practicalr shaped core to fit circular cylindrical coils.

The development of the transformer art, especially in the higher voltages, has lately turnedI towards circular coils. I-Ieretofore, the cores for circular coils have usually been made up of laminations of different sizes which complicates the Work and Wastes time and. material and increases the expense.

I believe it is a fact that from the standpoint of economical design the designer prefers to use shell type transformer construction in which the copper expense is only about 30 per centof the total cost against about l() per cent for the core type. But for structural reasons the shop stays by the core type. In this connection, my improved core when employed with small transformers belo\v 25 Kv. a. equals or betters shell type copper saving and has obvious structural .advantages comparable to the core type.

Moreover, I effect a further savingand better the transformer in other Ways Which are apparent from consideration of the geometrical form of coil bearing core leg section employed in Which:

lith a given perimeter 3.1416 inches, the areas of figures are as follows:

Figure. Area. Per cent.

Circle n 100.00 Hexagon Q0. 00 approx. Square 78. 00 approx. Rectangle 69. 0() approx.

lith a given area .7854 square inches,`

the perimeters of figures are as follows:

By following conventional design metln ods it is possible with my improved core to save 2Ov per cent under conventional core type cost and about 1Q percent under conventional shell type cost. And With the same cost and efficiency I am able to further improve the construction by compromise in use of material, whereby I secure greater space factors for the insulation and I employ this advantage tebetter the insulating medium and secure more uniform cooling.

' A. patent was granted Hassler in 1894 for a hexagon'core section so that I do not claim a hexagon core section broadly. Moreover the IAIassler patent has been public property for a matt-er of ten years or more during Which time certain advantages of the idea have been developed into other lpatents forming the basis of successfully built commercial transformers in which the makers by reason of the large number of their transformers in use and continuation of manufacture thereof bear testimony of the utility Aof such core section form with its advan- What I claim nev,7 and Wish to secure by Letters Patent of the Inited States, is,

l. In combination with a transforin-er, a laminated magnetic circuit therefor, a coil bearing core leg polygonal in cross section having a V-shaped section member composed of parallel plane laminae anda rliomb shaped section member composed of other parallel laminas departing from the plane of the said parallel plane laminas, a non-coil bearing core leg V-shaped in cross section composed of parallel plane laminas, common yoke laminie interleaved across opposite coil ends joining the said coil bearing and noncoil bearing tl-shaped section member parallel plane laminas, and yoke lamin having a bent end portion joining the said other parallel laminas having said departing plane composing the said rhomb-shaped section member to portions of said common yoke laminas and to portions of said coil bearing l and non-coil bearing parallel plane V-shaped section member laminas and interleaved therewith across opposite coil ends.

2. In a coil bearing transformer core leg polygonal in cross section, a section member composed of parallel plane laminae offset relative to each adjacent laminas producing surfaces forming substantially a V-shape, and also a section member composed of other parallel laminas offset relative to each adjacent laminte and having planes departing from the plane of the said parallel plane laminee and producing surfaces forming substantially a rhomb-shape.

3. The combination with a transformer, a laminated magnetic circuit therefor, a coil bearing core leg section composed of laminae of the same size, offset relative to each adjacent laminas in two part members to produce surfaces on the said part members each departing from the plane of the other, a non-coil bearing core section composed of laminas` offset relative to each adjacent laminas to produce surfaces corresponding to the surfaces of its adjacent said coil bearing core leg section part member and set parallel with same forming two adjacent depending core sections, end yoke lamin of a common width and two lengths, long bent angle end yoke laminas interleaved with the said two part member laminae'along their like plane portions, and short yoke laminas interleaved with the said long bent angle end yoke laminas and also interleaved with the said two adjacent depending core leg laminze.

d. In combination, a set of coil windings substantially cylindrical, a magnetic core leg polygonal in cross section through said coil windings and having a plurality of laminated members each vdeparting from the plane of the other, a depending laminated core leg set parallel with said polygonal coil bearing core leg and outside the said coil windings, the said coil bearing core leg and the said depending core leg` being connected by yoke laminas across the opposite ends of the said coil windings and forming a core body composed of laminations providing an opening through which the said coilwindingsfare disposed around.V the said polygonal core leg, the said yoke laminas having portions adapted to interleave with and join together the said polygonal laminated members each departing from the plane of the other,and the laminas compos ing the respective'said members and said depending core leg being so arrangedthat the coil spaceopening through the said core body is not straight through Vbut assumes a shape corresponding to surfaces of said members and said depending core leg where by the said coil windings fit snug in said opening.

5. The combination in an electrical transn former core or magnetic circuit, a coil bearn ing polygonal core leg section arranged forming a plurality of parts composed of parallel laminae arranged in the respective parts forming an equal plurality of planes in which the respective laminae lie, a noncoil bearing depending core leg section oomposed of parallel laminas and arranged in vl-shaped fashion, end yoke members com posed of lamime having portions adapted to connect the laminas planes of the said coil bearing polygonal core leg section parts to gether, and with the said end yoke members assuming substantially a rectangular shape through their middle portions whereby the .magnetic circuit is completed through the said polygonal core leg and the said depend- Ving core leg by common end yokes.

6. ln a transformer core or .magnetic circuit, a set or series of bent end laminas interleaved adjacent the bend with core laminas composing section members each departing from the plane of the other, and withsaid end laminae joining the complete magnetic circuit through laminated members common to the said section members each departing from the plane of the other.

7. The combination of bent end laminas in a transformer core, the said bent end laminas consisting of plates bent flatwise at an angle forming angle portions, and which said angle portions join a plurality of core sections connected through a magnetic circuit.

8. The combination in a transformer core or magnetic circuit, of laminae bent iiatwise in obtuse angle formation, and with the said bent laminas interleaved along its respective angles with a plurality of laminated mem bers in which the plane' of the respective laminze composing the said members determines the degree of angle of the said bent angle laminas.

9. In a 'coil bearing transformer core leg polygonal in cross section and composed of laminee of the same size,l a section member composed of parallel plane laminas offset relative to `each adjacent laminas producing surfaces forming substantially a troughshape on one side thereof, and a section member composed of other parallel plane l'taminae offset relative to each adjacent laminae tol produce a surface having porti-ons adapted to t against andA abut said trouglr shaped surface.

I0. In a transformer Core or magnetic circuit of theV Character described, a coil bearing laminated Core leg composed of two members each. departing fromtlie plane of the other and arranged toy form a polygonal W cross' section, a. depending core leg set outside the coil and composed of parallel plane lamina@ forming substantially a V-shaped cross section, and common laminated yoke members joining said legs together on opposite ends thereof and having Lmiddle portions substantially rectangular in cross section.

In testimony I aflix my signature. Ogden, Arkansas, September 5, 1921.

CHARLES M. W'ELCH. 

